Setipiprant for hair loss: How Exactly Does it Work?

Setipiprant is a relatively new drug in the world of hair loss medications. It’s taken orally and is known as a prostaglandin D2 receptor (PGD2R) antagonist. Prostaglandin D2 is a lipid compound that has hormone like effects in mammals. So a prostaglandin D2 receptor antagonist prevents PGD2 from being effective in the body (or locally in the scalp), thus preventing hair loss.

Using wound-induced hair follicle neogenesis (WIHN) as a marker of skin regeneration, we hypothesized that PGD2 decreases follicle neogenesis. PGE2 and PGD2 were elevated early and late respectively during wound healing… Additionally, an alternatively spliced transcript variant of Ptgds missing exon 3 correlated with high regeneration in mice. …Furthermore, Gpr44 null mice were resistant to PGD2-induced inhibition of follicle neogenesis. In all, these findings demonstrate that PGD2 inhibits hair follicle regeneration through the Gpr44 receptor and imply that inhibition of PGD2 production or Gpr44 signaling will promote skin regeneration.

Setipiprant was well tolerated after single- and multiple-dose administration. Headache was the most frequently reported adverse event. No treatment effect on tolerability variables was observed. After single- and multiple-dose administration, setipiprant was rapidly absorbed and followed a biphasic elimination pattern with an elimination half-life between 10 and 18h. Steady-state conditions were reached after 2-3 days and setipiprant did not accumulate. Exposure to setipiprant was lower in the presence of food. Urinary excretion of unchanged setipiprant did not exceed 7% of the administered dose. In this entry-into-human study, setipiprant showed good tolerability and a favorable PK profile, thus warranting its development in the treatment of inflammatory disorders.

How effective is setipiprant?

Setipiprant is currently going through a Phase 2A Study to test it’s efficacy. It is believed that the pills in 1000mg potency, twice daily, will help alleviate male pattern hair loss. It is not certain what the effects of the pill would be for women, and the Phase 2A Study has not yet concluded.

The study has an inclusion criteria that the “Participant has androgenetic alopecia (AGA) [and] Participant agrees to maintain current hair care regimen, refraining from hair weaving, hair colorants or dyes and non-study hair growth products during the study.” However, those who have hair loss for other reasons besides Male Pattern Baldness were excluded from the study. Other exclusionary criteria would be damage or scarring of the scalp, and taking of drugs that would impact hair growth within 6 months of the study.

It is unknown if the pills will increase hair growth, but there is promise behind the study. The Phase 2A study is not supposed to conclude until June of 2018, and includes 169 subjects, including placebo controls. Hopefully when the study results are posted, we will find out the efficacy of this growing new hair loss drug.